Mobile communication devices generally include circuitry for determining a location or position of the device. When the mobile communication device is outside in open sky conditions, position may be determined using GNSS (Global Navigation Satellite System) signals received from GNSS satellites. When the mobile communication device is inside, the GNSS signal is generally too weak to be used effectively. As an alternative, the mobile device may determine an indoor position using a signal obtained from a terrestrial-based positioning system such as terrestrial-based pseudo-satellites (or “pseudolites”). Pseudolites transmit positioning signals using the Multilateration Location and Monitoring Service (M-LMS) frequency band, which ranges from about 902 Megahertz (MHz) to about 928 MHz. The mobile communication device may therefore include a pseudolites positioning engine for determining position using pseudolite positing signals. The pseudolites positioning engine operates off of a clock of the device. The accuracy of the position obtained using the pseudolites positioning engine depends on the clock bias and/or a frequency drift of the clock and aging characteristics of the reference oscillator or clock.